1. Field of the Invention
The present invention relates to a method and an apparatus for detecting fluorescence for determining conditions of organic tissue based on autofluorescence emitted therefrom in response to stimulating light projected thereon, and more particularly, to a method and an apparatus for distinguishing between the mucosa and the sub mucosa by detecting fluorescence emitted from the organic tissue.
2. Description of the Related Art
Endoscopic mucosal resection (hereinafter, called EMR) has been widely used as a remedy for cancer in which a lesion on a mucosa affected with cancer in early stages is extirpated while being observed with an endoscope. EMR is an effective remedy which is less invasive than surgical remedies. EMR is directed at cancer in its early stages which has affected a mucosa of organic tissue but has not yet affected a sub mucosa thereunder. The mucosa affected with cancer in its early stages is extirpated using a treating instrument for resection guided thereto by the endoscope.
However, even if an affected area on the mucosa is extirpated through the EMR treatment, it may sometimes result in incomplete removal of the mucosa and an unremoved lesion affected with cancer (hereinafter, called residual) may still reside on a fraction of the mucosa remaining on the treated area. An incidence of the residual is low in the case where the affected area is small and the entire lesion on the mucosa can be extirpated with a single resection process. However, in the case where the affected area is large and a plurality of resection processes must be performed, the incidence of the residual becomes higher as the number of the resection processes increases. Whether or not the mucosa is remaining on the treated area after the EMR treatment is judged by examining a condition of the organic tissue sampled from the treated area. Such examination takes a considerable time and requires additional endoscopic treatment. Therefore, though EMR is a non-invasive and effective remedy, it has a disadvantage of making it difficult to check if the treatment was completely done immediately after the treatment.
The objective of the present invention is to provide a method and an apparatus for detecting fluorescence to distinguish between a sub mucosa and a mucosa immediately and easily.
In the first method of the present invention, a sub mucosa of organic tissue is distinguished from a mucosa thereof based on autofluorescence emitted from the organic tissue in response to stimulating light projected thereon, wherein the sub mucosa is distinguished from the mucosa based on the normalized intensity of the autofluorescence emitted from the organic tissue utilizing the fact that the spectrum of autofluorescence emitted from the sub mucosa is different from the spectrum of autofluorescence emitted from the mucosa.
In the second method of the present invention, judgment is made on whether or not a sub mucosa and a mucosa coexist on the area under examination based on autofluorescence emitted from organic tissue within the area under examination in response to stimulating light projected thereon, wherein the judgment is made by comparing the normalized intensity of the autofluorescence emitted from the organic tissue with a standard value which is decided based on the normalized intensity of autofluorescence emitted from the sub mucosa and/or the normalized intensity of autofluorescence emitted from the mucosa.
In the third method of the present invention, judgment is made on whether the organic tissue under examination is of a sub mucosa or a mucosa based on autofluorescence emitted from the organic tissue in response to stimulating light projected thereon, wherein the judgment is made by comparing the normalized intensity of the autofluorescence emitted from the organic tissue with a standard value which is decided based on the normalized intensity of autofluorescence emitted from the sub mucosa and/or the normalized intensity of autofluorescence emitted from the mucosa.
The first apparatus of the present invention comprises distinguishing means for distinguishing a sub mucosa of organic tissue from a mucosa thereof based on autofluorescence emitted from the organic tissue in response to stimulating light projected thereon, wherein the distinguishing means distinguishes the sub mucosa from the mucosa based on the normalized intensity of the autofluorescence emitted from the organic tissue utilizing the fact that the spectrum of autofluorescence emitted from the sub mucosa is different from the spectrum of autofluorescence emitted from the mucosa.
The second apparatus of the present invention comprises distinguishing means for making judgment on whether or not a sub mucosa and a mucosa coexist on the area under examination based on autofluorescence emitted from organic tissue within the area under examination in response to stimulating light projected thereon, wherein the distinguishing means makes judgment by comparing the normalized intensity of the autofluorescence emitted from the organic tissue with a standard value which is decided based on the normalized intensity of autofluorescence emitted from the sub mucosa and/or the normalized intensity of autofluorescence emitted from the mucosa.
The third apparatus of the present invention comprises distinguishing means for making judgment on whether the organic tissue under examination is of a sub mucosa or a mucosa based on autofluorescence emitted from the organic tissue in response to stimulating light projected thereon, wherein the distinguishing means makes judgment by comparing the normalized intensity of the autofluorescence emitted from the organic tissue with a standard value which is decided based on the normalized intensity of autofluorescence emitted from the sub mucosa and/or the normalized intensity of autofluorescence emitted from the mucosa.
Each of the normalized intensities to be used with the methods and apparatuses described above is preferably the normalized band intensity for a wavelength region near 480 nm.
Each of the above apparatuses for detecting fluorescence may additionally comprise optical fiber means for transferring the autofluorescence emitted from the organic tissue which is incident on one end thereof to the distinguishing means, wherein the optical fiber means may be run through a tube path extending between a handling portion and the operating end of an endoscope.
The tube path through which the optical fiber means is run may be led through an inner area of a treating instrument of the endoscope.
The inventors of the present invention noticed in the course of the studies on techniques for detecting fluorescence that it is possible to distinguish the sub mucosa from the mucosa utilizing the fact that the fluorescence emitted from the sub mucosa and the fluorescence emitted from the mucosa present different distributions of the spectral intensity even if induced by the same stimulating light. The present invention is based on such findings.
According to the methods and the apparatuses of the present invention for detecting fluorescence, it is possible to distinguish the sub mucosa from the mucosa based on the normalized intensity of the autofluorescence emitted from the organic tissue in response to stimulating light projected thereon utilizing the fact that the spectrum of the autofluorescence emitted from the sub mucosa is different from the spectrum of the autofluorescence emitted from the mucosa (the first method and apparatus for detecting fluorescence), to judge whether or not the sub mucosa and the mucosa coexist on the treated area by comparing the normalized intensity of the autofluorescence emitted from the organic tissue with the standard value which is decided based on the normalized intensity of autofluorescence emitted from the sub mucosa and/or the normalized intensity of autofluorescence emitted from the mucosa (the second method and apparatus for detecting fluorescence), or to distinguish the sub mucosa from the mucosa by comparing the normalized intensity of the autofluorescence emitted from the organic tissue with the standard value which is decided based on the normalized intensity of autofluorescence emitted from the sub mucosa and/or the normalized intensity of autofluorescence emitted from the mucosa (the third method and apparatus for detecting fluorescence). With each method or apparatus, the sub mucosa can easily be distinguished from the mucosa based on the normalized intensity of the autofluorescence. The present invention therefore enables us to check whether the EMR treatment was completely done immediately after the treatment by examining whether the entire mucosa on the treated area has been completely removed revealing the sub mucosa thereunder, instead of, for example, requiring us to sample the organic tissue from the treated area and examine whether or not the diseased tissue is remaining thereon by way of time-consuming tissue inspection carried out after the EMR treatment. Thus, the time required for the check can be remarkably shortened. If the mucosa still remained on the treated area partially, the EMR treatment could be repeated until the entire mucosa would be removed from the area.
Accuracy of the above distinction can be further improved by using the normalized band intensity taken for a wavelength region near 480 nm.
In addition, the distinction can be practiced more easily by providing the apparatus for detecting fluorescence with the optical fiber means for transferring the autofluorescence incident on one end thereof to the distinguishing means and running the optical fiber means through the tube path connecting the handling portion and the operating end of the endoscope. The tube path through which the optical fiber means is run may be led through the inner area of the treating instrument of the endoscope.